Sheaf-based fluid filter

ABSTRACT

A thread-based filter comprising: a thread-based medium comprising multiple threads; and a tube, wherein the tube at least partially houses the thread-based medium with the threads oriented lengthwise along the length of the tube, and wherein the thread-based medium is configured to trap impurities present in a fluid flowing substantially lengthwise along the threads during a filtration mode, and wherein the thread-based medium is configured to release impurities into a fluid flowing substantially lengthwise along the threads during a washing mode.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/917,617, entitled “Sheaf-Based Fluid Filter,” filed Mar. 9, 2016,which is a national phase of PCT Patent Application No.PCT/IL2014/050800 filed on Sep. 9, 2014, which claims the benefit ofpriority of Great Britain Patent Application No. 1316007.2 filed on Sep.9, 2013. The contents of the above applications are all incorporated byreference as if fully set forth herein in their entirety.

FIELD OF THE INVENTION

The invention relates to the field of fluid filters.

BACKGROUND

Fluid filters are designed to remove solid or other impurities from afluid (liquid and/or gas) by means of a porous physical barrier. Thephysical barrier is often referred to as the “filter medium”. Many typesof filter media exist. Some filter media are compressible, allowing anadjustment of the size and/or shape of their pores, thereby enabling theremoval of impurities of different sizes and/or shapes. Other filtermedia remove impurities by means of interception and causing adherenceof the particles, requiring water to flow flows at a relatively slowrate.

In addition to their filtering mode of operation, fluid filters areoften also configured to be operated in a washing mode. In the washingmode, a fluid is streamed in the opposite direction to the filteringdirection, thereby washing away the impurities previously caught in thefilter medium. In some cases, the media may be expanded before or duringthe washing, thereby allowing the caught impurities to escape from thepores into the washing fluid.

One common type of fluid filters is a water filter. Water filters areused, for example, in water treatment plants, desalination plants, andpoints-of-use, such as residential or commercial sites. These filtersmay filter water intended for drinking, irrigation and/or industrialpurposes, removing impurities ranging from dirt to pathogens.

The foregoing examples of the related art and limitations relatedtherewith are intended to be illustrative and not exclusive. Otherlimitations of the related art will become apparent to those of skill inthe art upon a reading of the specification and a study of the figures.

SUMMARY

The following embodiments and aspects thereof are described andillustrated in conjunction with systems, tools and methods which aremeant to be exemplary and illustrative, not limiting in scope.

There is provided, in accordance with an embodiment, a thread-basedfilter, comprising: a thread-based medium comprising multiple threads;and a tube comprising a first opening and a second opening, wherein thetube at least partially houses the thread-based medium, the mediumhaving a first end oriented towards the first opening and a second endoriented towards the second opening, wherein the threads are orientedlengthwise along the length of the tube and extend between the first andsecond ends of the medium, and wherein the thread-based medium isconfigured to trap impurities present in a fluid flowing substantiallylengthwise along the threads from the first opening to the secondopening during a filtration mode, and wherein the thread-based medium isconfigured to release impurities into a fluid flowing substantiallylengthwise along the threads from the second opening to the firstopening during a washing mode.

In some embodiments, the threads at the second end of the medium areattached to a plate, and wherein the threads at the first end of themedium are unattached, thereby providing a smaller inter-thread spacingduring the filtering mode and providing a greater inter-thread spacingduring the washing mode.

In some embodiments, the medium is tapered towards the second end of themedium.

In some embodiments, the plate provides a passageway for the fluid.

In some embodiments, the medium is configured to move lengthwise alongthe tube.

In some embodiments, the motion of the medium lengthwise along the tubeis configured to provide a varying inter-thread spacing within themedium.

In some embodiments, the tube comprises a narrow portion and a wideportion.

In some embodiments, the thread based medium is housed in the narrowportion during the filtration mode, and wherein the at least a portionof the medium adjacent to the first end of the medium is housed in thewide portion of the tube during the washing mode.

In some embodiments, the thread based medium is at least partiallycontained within the tube during the filtration mode, and wherein atleast a portion of the medium adjacent to the first end of the medium isexposed from the tube during a washing mode.

In some embodiments, the fluid is any of water, air or a combination ofwater and air during a washing mode.

In some embodiments, the fluid is introduced to the medium as acontinuous stream during a washing.

In some embodiments, the fluid is introduced to the medium as a pulseduring a washing mode

There is further provided, in accordance with an embodiment, amulti-sheaf-based filter, comprising: multiple sheaf-based filter units;and a filter body, wherein the filter body is configured to house themultiple sheaf-based filter units.

In some embodiments, the sheaf-based filter units each comprise thethread-based filter.

In some embodiments, the multi-sheaf-based filter further comprises: afiltering input port; a filtering output port; a washing input port; anda washing output port, wherein the multi-sheaf based filter isconfigured to receive a filtration fluid at the filtering input port,direct the filtration fluid into the multiple sheaf-based filter unitsto flow lengthwise along the threads of the units, and remove thefiltration fluid via the filtering output port, thereby filtering thefiltration fluid, and receive a washing fluid at the washing input port,direct the washing fluid into the multiple sheaf-based filter units toflow lengthwise along the threads of the units, and remove the washingfluid via the washing output port, thereby washing the filter.

In some embodiments, the filter is configured to direct the fluid intothe units simultaneously.

In some embodiments, the filter is configured to direct the fluid intothe units sequentially.

There is further provided, in accordance with an embodiment, a methodfor filtering a fluid, the method comprising: introducing a fluid into athread-based medium comprising multiple threads extending between afirst end and a second end of the medium, wherein the medium is at leastpartially housed in a tube, and wherein the threads of the medium areoriented lengthwise along the length of the tube with the first end ofthe medium oriented with a first end of the tube and the second end ofthe medium oriented with a second end of the tube, directing the fluidto flow lengthwise along the threads from the first end of the medium tothe second end of the medium; trapping in the threads impurities presentin the fluid, thereby filtering the fluid; and removing the fluid fromthe second end of the medium.

In some embodiments, directing the fluid to flow from the first end ofthe medium to the second end of the medium further comprises directingthe fluid to flow from the unattached ends of the threads at the firstend of the medium to a plate attached to the second end of the medium.

In some embodiments, trapping further comprises pushing the mediumlengthwise along the tube, thereby containing the medium within the tubeand reducing the inter-thread spacing of the medium.

In some embodiments, the tube has a varying cross-sectional area, andwherein the medium is at least partially contained within a narrowerportion of the tube.

In some embodiments, the second end of the medium is tapered.

There is further provided, in accordance with an embodiment, a methodfor washing a filter, the method comprising: introducing a fluid into asecond end of a thread-based medium comprising multiple threadsextending between a first end and a second end of the medium, whereinthe medium is at least partially housed in a tube, and wherein thethreads of the medium are oriented lengthwise along the length of thetube with the first end of the medium oriented with a first end of thetube and the second end of the medium oriented with a second end of thetube, directing the fluid to flow lengthwise along the threads from thesecond end of the medium to the first end of the medium; releasingimpurities trapped in the threads into the fluid, thereby washing thefilter; and removing the fluid from the first end of the medium.

In some embodiments, directing further comprises directing the fluid toflow through a plate attached to the second end of the medium to theunattached ends of the threads at the first end of the medium.

In some embodiments, releasing further comprises pushing the mediumlengthwise along the tube, thereby exposing at least a portion of themedium adjacent to the first end of the medium from the tube andincreasing the inter-thread spacing of the medium.

In some embodiments, releasing further comprises pushing the mediumlengthwise along the tube, thereby containing the at least a portion ofthe medium adjacent to the second end of the medium in a wider portionof the tube and increasing the inter-thread spacing of the medium

In some embodiments, the fluid comprises water, or air, or a combinationof water and air.

In some embodiments, the fluid is introduced as a continuous stream.

In some embodiments, the fluid is introduced as a pulse.

In addition to the exemplary aspects and embodiments described above,further aspects and embodiments will become apparent by reference to thefigures and by study of the following detailed description.

BRIEF DESCRIPTION OF THE FIGURES

Exemplary embodiments are illustrated in referenced figures. Dimensionsof components and features shown in the figures are generally chosen forconvenience and clarity of presentation and are not necessarily shown toscale. The figures are listed below.

FIG. 1A shows a cross-sectional view of an exemplary sheaf-based filterduring a filtration mode, in accordance with an embodiment of theinvention;

FIG. 1B shows a cross-sectional view of the exemplary sheaf-based filterof FIG. 1A during a filtration mode, in accordance with an embodiment ofthe invention;

FIG. 2A shows a cross-sectional view of an exemplary sheaf-based filterduring a filtration mode, in accordance with another embodiment of theinvention;

FIG. 2B shows a cross-sectional view of the exemplary sheaf-based filterof FIG. 1B during a filtration mode, in accordance with an embodiment ofthe invention;

FIG. 3A shows a flowchart of a method for filtering a fluid, inaccordance with the filter of FIG. 1A;

FIG. 3B shows a flowchart of a method for washing a filter, inaccordance with the filter of FIG. 1B;

FIG. 4A shows a flowchart of a method for filtering a fluid, inaccordance with the filter of FIG. 2A;

FIG. 4B shows a flowchart of a method for washing a filter, inaccordance with the filter of FIG. 2B;

FIGS. 5A-B show a cross-sectional view of an exemplary multi-sheaf-basedfilter, according to an embodiment of the invention;

FIG. 6A shows a flowchart of a method for filtering a fluid, inaccordance with the filter of FIGS. 5A-B; and

FIG. 6B shows a flowchart of a method for washing a filter, inaccordance with the filter of FIGS. 5A-B.

DETAILED DESCRIPTION

A thread-based fluid filter is disclosed herein. In this filter,multiple threads, such as in a sheaf configuration, provide abi-directional medium for alternate filtering and washing modes.Filtering and washing is achieved by streaming a fluid substantiallylengthwise along the threads in opposing directions, accordingly. Theterm “substantially” refers to the fact that while the majority of theflow may be lengthwise along the threads, some flow may be transverse orlateral to some of the threads, resulting in some cross flow.

Reference is now made to FIG. 1A, which shows a cross-sectional view ofan exemplary sheaf-based filter 100, in accordance with an embodiment ofthe invention. Filter 100 may include a thread-based filtration medium102 providing multiple threads, such as in a sheaf configuration, wherethe threads of the medium extend from one end of the medium to the otherend. Filter 100 may be configured to remove impurities from a fluidflowing lengthwise along the threads during a filtration mode, andrelease those impurities into a fluid flowing lengthwise along thethreads during a washing mode. The fluid, in accordance with someexemplary embodiments, may be water, air, oil, or combinations thereof,to name a few.

For example, in various embodiments, the number of threads per sheaf isbetween 120,000 and 130,000. The threads may be mono-filament having atypical diameter ranging between 200-250 microns. Alternatively, thethreads may be spun threads, each composed of approximately 70 singlemono-filament polyester fibers with typical thread diameters rangingfrom 200 to 250 microns. A typical filtration unit may have anapproximate diameter of 8 cm, and a height of between 10 and 15 cm.However, other sizes of filtration units are intended herein.

The term “threads”, as referred to herein, may relate to any kind ofstrings, yarns, fabric stripes, etc.—whether having an essentially roundcross section, essentially rectangular cross section, etc. The threadsmay be made of any suitable material, whether rigid or flexible.

Medium 102 may be at least partially housed in a tube 104 disposed withone or more openings 106 a and 106 b for introducing and removing thefluid. Medium 102 may be oriented in a manner to allow the threads ofmedium 102 to run lengthwise along the length of tube 104, by orientingone end of medium 102 with opening 106 a and orienting the other end ofmedium 102 with opening 106 b, thereby allowing a fluid flowing throughthe tube to flow lengthwise along the threads of medium 102. In someembodiments, the cross-sectional area of tube 104 may have a circular orelliptical shape. In other embodiments the cross-sectional area of tube104 may have a polygon shape, such as a hexagon, triangle or square, toname a few.

The threads of medium 102 may be attached at one end, such as byattaching the ends of the threads to a plate, such as a disc 108. Medium102 may be configured to move lengthwise along tube 102, such as byconfiguring plate 108 to move lengthwise along tube 102, such as inresponse to fluid pressure. The threads may be attached to plate 108using any suitable attachment technique, such as by gluing the threadsto plate 108 using any suitable adhesive. Plate 108 may provide one ormore passageways for fluid to flow through plate 108, such as one ormore perforations. The opposite ends of the threads of medium 102 may beoptionally unattached. A rod 110 may be coupled to plate 108 at an endof tube 104 via a bridge 112. Rod 110 may provide a stabilizing axis toplate 108 for lengthwise aligning the motion of plate 108 along tube104, such as in response to fluid pressure. Optionally, the lengthwisemotion of rod 110 for pushing and/or pulling plate 108 along tube 102may be augmented using any suitable means, such as by applying anycombination of mechanical, electric, or pneumatic means to enhance thefiltering and washing operations. A seal 114, such as a polymeric sealmay be provided to prevent fluid leakage.

The following description discloses multiple modes of use for filter100, such as a filtering mode and a washing mode. In describing variouselements of the system, the terms ‘top’ and ‘bottom’ may be understoodas identifying opposite ends of the filter, and do not imply anyspecific orientation of the filter.

During a filtration mode, the fluid may be introduced to medium 102,such as at the unattached and optionally exposed ends of the threads.The fluid may enter from the bottom of tube 104 via opening 106 a, andflow substantially lengthwise along the threads towards opening 106 b.The fluid pressure, optionally augmented withelectro/mechanical/pneumatic means, may push medium 102 attached toplate 108 along tube 104 until plate 108 engages with the top end oftube 104, pushing medium 102 against plate 108 and at least partiallycontaining medium 102 within tube 104, thereby decreasing theinter-thread spacing within the threads of the medium. Impurities, alsoreferred to as “particles”, that are present in the fluid may flow intothe spaces between the threads, starting from the free ends of themedium 102 until they reach a location where the space is too tight toaccommodate them, and they become trapped in the threads, therebyfiltering the fluid. The particles may be trapped in the threads byadditional means, such as by interception by the threads, internalimpaction, diffusion, or Electro kinetic effects, thereby filtering thefluid. The filtered fluid may flow out of medium 102 through theperforations in plate 108 and exit from the top of tube 104 via opening106 b.

Reference is now made to FIG. 1B, which illustrates the filter of FIG.1A during an exemplary washing mode. In the example of FIG. 1B, awashing fluid may be introduced to medium 102, such as at the attachedends of the threads of the medium, via opening 106 b at the top of tube104. The washing fluid may flow through the perforations of plate 108substantially lengthwise along the threads of medium 102 in tube 104towards opening 106 a. The washing fluid, optionally augmented withelectro/mechanical/pneumatic means, may push medium 102 attached toplate 108 lengthwise along tube 104 until a portion of the threads, suchas the portion adjacent to the unattached ends of the threads, areexposed from the bottom of tube 104, allowing the threads to separate,and increasing the inter-thread spacing in medium 102. Impurities thatwere trapped in the threads may be pushed out of medium 102 by thewashing fluid and released into the fluid, thereby washing the filter.The washing fluid with the impurities may exit tube 104 via opening 106a.

Reference is now made to FIGS. 2A-B, which illustrate an exemplarysheaf-based filter according to another embodiment of the invention. Inthe example of FIGS. 2A-B, Filter 200 is substantially similar to filter100 of FIG. 1A with the notable difference that tube 204, correspondingto tube 104 of FIG. 1A, is configured with a tapered geometry providinga varying cross-sectional area along its length, such as by configuringa top portion of tube 204 a with a narrower cross-sectional area than awider, bottom portion of tube 204 b. For example, in some embodimentstypical ratios between the cross-sectional areas of portion 204 a toportion 204 b may range from 1:15 to 1:1.25, or an increase of between15% to 25%. Other embodiments may have different ratios between theportions. In one embodiment, narrow tube portion 204 a and wide tubeportion 204 b may be cylindrical and may connect to each other using anysuitable connector, such as with a conical mid-portion 204 c. The lengthof narrow tube portion 204 a may be sufficient to contain the threads ofmedium 202 within tube portion 204 a when plate 208 engages with the topof narrow tube portion 204 a, such as during the filtering mode when thefluid flows lengthwise along the threads of medium 202 from opening 206a to opening 206 b. Advantageously, engaging plate 208 with the top ofnarrow portion 204 a causes the threads to become crowded and reducesthe inter-thread spacing of medium 102, thereby enhancing the filteringcapability of medium 202. The threads of medium 202 may be optionallytapered towards their attachment to plate 208, thereby further reducingthe inter-thread spacing when plate 208 engages with the top of tube 204and enhancing the filtration capability of medium 202.

Reference is now made to FIG. 2B which illustrates the filter of FIG. 2Ain a washing mode of operation. Advantageously, the length of tube 204may be sufficient to contain the threads of medium 202 throughout thewashing mode, without exposing any portion of the threads out of tube204. When plate 208 is pushed lengthwise along tube 204 by the washingfluid, such as during the washing mode when the fluid flows lengthwisealong the threads of medium 202 from opening 206 b to opening 206 a,optionally augmented with electro/mechanical/pneumatic means, at least aportion of medium 202, such as the portion of the threads that areadjacent to the free, unattached ends of the threads, may be containedwithin wide tube portion 204 b causing the threads of medium 202 toseparate and increasing the inter-thread spacing, thereby enhancing thewashability of medium 202. Impurities that were trapped in the smallerinter-thread spaces may be released into the washing fluid.Advantageously, preventing the exposure of the threads of medium 202from tube 204 shields and protects them from becoming entangled, such aswith other threads.

In some embodiments, multiple cycles, such as the washing cycle, may beperformed with filters 100 and 200 using different compositions offluid, such as performing alternating cycles with water, air, or acombination of water and air. In some embodiments the fluid isintroduced into mediums 102 and 202 in pulses, whereas in otherembodiments the fluid is introduced as a continuous stream.

Advantageously, by attaching the optionally tapered threads at one endto a plate, and leaving the threads unattached at their other ends, andfurther providing the plate mobility within either of tubes 104 or 204,a varying inter-thread spacing is provided to the thread mediumthroughout the usage modes described above, thereby enhancing both thefiltering and washing operations. In this manner, in some embodiments afiltration fineness of approximately 1 micron may be achieved. In otherembodiments a different filtration fineness may be achieved.

Reference is now made to FIG. 3A which is a simplified flowchart of amethod for filtering a fluid, in accordance with an embodiment of theinvention. In the method of FIG. 3A, a fluid to be filtered may beintroduce, such as by pumping the fluid, into the optionally exposed andunattached bottom thread ends of a thread-based medium comprisingmultiple threads extending from one end of the medium to the other end,to flow substantially lengthwise along the threads of the medium towardsthe attached ends of the threads (Step 300). The fluid may directed toflow into the bottom of a tube housing at least a portion of the mediumwith the threads running lengthwise along the length of the tube, wherethe unattached ends of the medium may be oriented with the bottom of thetube (Step 302). The fluid may push a plate attached to the top ends ofthe threads and oriented with the top of the tube, lengthwise along thetube, engaging the plate with the top of the tube (Step 304), therebycontaining at least a portion of the thread-based medium in the tube andcrowding the threads by reducing the inter-thread spacing (Step 306).Impurities present in the fluid may be trapped in the threads, therebyfiltering the fluid (Step 308). The filtered fluid may be removed byflowing out of the medium through one or more perforations in the plate,and may exit from the top of the tube via an opening (Step 310).

Reference is now made to FIG. 3B which is a simplified flowchart of amethod for washing a filter, in accordance with an embodiment of theinvention. In the method of FIG. 3B, a washing fluid may be introduced,such as by pumping the fluid in a continuous stream or alternately as apulse, into the top of a tube at least partially housing a thread-basedfilter medium comprising multiple threads extending from one end of themedium to the other end (Step 320). The fluid may be directed to flowsubstantially lengthwise along the threads within the tube (Step 322).The washing fluid may flow through one or more perforation in a platethat is attached to the top of the medium oriented with the top of thetube towards the optionally unattached ends of the threads oriented withthe bottom of the tube (Step 324). The washing fluid may push the platelengthwise along the tube, thereby exposing at least the bottomunattached ends of the thread-based medium from the bottom end of thetube (Step 326). The threads may separate, such as towards their bottomportions, and the inter-thread spacing of the medium may increase (Step328). Impurities trapped in the threads may be released into the washingfluid (Step 330), thereby washing the filter. The washing fluid may exitfrom the bottom of the tube and be removed from the medium (Step 332).To enhance the washing, a combination of water and air, or a combinationof a different liquid with air, may be used as the washing fluid. Theair may form bubbles in the water or the different fluid, and, thereby,the threads and their trapped impurities may be intermittently hit withwater and air, shocking them and assisting in releasing the impurities.Alternatively, only air may be used as the washing fluid, for at least acertain duration during the washing.

Reference is now made to FIG. 4A which is a simplified flowchart of amethod for filtering a fluid, in accordance with an embodiment of theinvention. In the method of FIG. 4A, a fluid to be filtered may beintroduced, such as by pumping the fluid through an opening disposed atthe bottom of a wide portion of a tube configured with a varyingcross-sectional area along its length and housing a thread-basedfiltration medium, oriented with the threads running lengthwise alongthe length of the tube (Step 400). The fluid may be directed into theunattached threads of the medium to flow substantially lengthwise alongthe threads of the medium towards the attached, optionally tapered endsof the threads (Step 402). The fluid may push a plate attached to thetop ends of the threads along the narrow tube portion, engaging theplate with the top of the narrow tube (Step 404). The fluid may push themedium lengthwise along the tube into the narrow tube portion (Step406). The threads of the medium may be contained within the narrow tubeportion, crowding the threads by reducing the inter-thread spacing ofthe medium (Step 408). Impurities present in the fluid may be trapped inthe threads (Step 410), thereby filtering the fluid. The filtered fluidmay be removed from the medium by flowing out through one or moreperforations in the plate, and exit from the narrow tube portion via anopening (Step 412).

To enhance the washing, a combination of water and air, or a combinationof a different liquid with air, may be used as the washing fluid. Theair may form bubbles in the water or the different fluid, and, thereby,the threads and their trapped impurities may be intermittently hit withwater and air, shocking them and assisting in releasing the impurities.Alternatively, only air may be used as the washing fluid, for at least acertain duration during the washing.

Reference is now made to FIG. 4B which is a simplified flowchart of amethod for washing a filter, in accordance with another embodiment ofthe invention. In the method of FIG. 4A, a washing fluid may beintroduced, such as by pumping the washing fluid in a continuous streamor alternately as a pulse, through an opening disposed at the top of anarrow portion of a tube configured with a varying cross-sectional areaalong its length and housing a thread-based filtration medium orientedwith the threads running lengthwise along the length of the tube (Step420). The washing fluid may be directed to flow substantially lengthwisealong the threads of the medium (Step 422). The washing fluid may flowthrough one or more perforation in a plate that is attached to the topends of the threads of the medium (Step 424). The washing fluid may pushthe plate lengthwise along the tube thereby enclosing at least thebottom free ends of the threads within a wide portion of the tube (Step426). The threads may separate within the wide portion of the tube,thereby increasing the inter-thread spacing of the medium (Step 428).Impurities trapped in the threads may be released into the washingfluid, thereby washing the filter (Step 430). The washing fluid may flowout of the medium through an opening disposed at the bottom of the wideportion of the tube (Step 432).

To enhance the washing, a combination of water and air, or a combinationof a different liquid with air, may be used as the washing fluid. Theair may form bubbles in the water or the different fluid, and, thereby,the threads and their trapped impurities may be intermittently hit withwater and air, shocking them and assisting in releasing the impurities.Alternatively, only air may be used as the washing fluid, for at least acertain duration during the washing.

Reference is now made to FIG. 5A which shows a cross-sectional view ofan exemplary multi-sheaf-based filter, in accordance with anotherembodiment of the invention. A filter house 520, which may include afilter body 522 attached to a filter cover 524 may house multiplethread-based filter units 500, corresponding to any of filter units 100or 200, described above. Body 522 may be attached to cover 524 using anysuitable attaching technique, such as by using a plurality of screws.Body 522 may be sealed to cover 524, for example using one or morepolymeric seals, to prevent fluid leakage. Filter house 520 may providefiltering ports 526 a and 526 b coupled to filtering pipes 528 a and 528b, respectively, for introducing and removing fluids from filter units500 during the filtering mode. Similarly, house 520 may provide washingports 530 a and 530 b coupled to washing pipes 532 a and 532 b,respectively, for introducing and removing fluids from filter units 500during the washing mode. The ports and pipes may be configured to directfluid flowing in any orientation to flow vertically into and out ofunits 500.

For example a filtration fluid may be received horizontally into filterhouse 520 via input filtering port 526 a disposed towards the bottom ofbody 522. Input filtering pipe 528 a may direct the fluid to flowvertically upwards into units 500, so that the fluid flows lengthwisealong the threads of mediums 502, corresponding to medium 102, inaccordance with the filters described above in FIGS. 1A-B and 2A-B. Thefluid may be removed by exiting from units 500 via output filtering pipe528 b in a substantially vertical orientation and be directed to flowhorizontally out of filter house 520 via output filtering port 526 bdisposed at the side of cover 524, thereby filtering the filtrationfluid.

Similarly, a washing fluid may be introduced horizontally into filterhouse 520 via input washing port 530 a situated at the side of cover524. Input washing pipe 532 a may direct the fluid to flow verticallydownwards into units 500, so that the fluid flows lengthwise along thethreads of mediums 502, corresponding to medium 102, in accordance withthe filters described above in FIGS. 1A-B and 2A-B. The washing fluidmay exit from units 500 via output washing pipe 532 b in a substantiallyvertical orientation and be directed to flow horizontally out of filterhouse 520 via output washing port 526 b disposed towards the bottom ofbody 524.

Reference is now made to FIG. 5B which shows another cross-sectionalview of the multi-sheaf-based filter of FIG. 5A, in accordance with anembodiment of the invention. Filter house 520 may encase a sheaf house534 that is disposed with multiple receptacles 536 for containing themultiple thread-based filter units 500, thereby disposing units 500 forthe filtering and washing modes described above. Units 500 may beindividually inserted into receptacles 536 and positioned vertically insheaf house 534 by inserting rods 510, corresponding to rods 510 above,through supporting crossbars 538. In one embodiment, the sheaf house maycontain up to 50 sheaf-based filtering units. In other embodiments, thesheaf house may contain 50 or more sheaf-based filtering units.

Reference is now made to FIG. 6A which is a simplified flowchart of amethod for filtering a fluid using a multi-sheath-based filter, inaccordance with an embodiment of the invention. In the method of FIG.6A, a filtering fluid may be introduced at the bottom of amulti-sheath-based filter (Step 600). The fluid may be directed into asealed body, optionally filling a cavity enclosed by the body, where thebody contains multiple sheath-based filtering units corresponding to anyof units 100 and 200 described above (Step 602). The fluid may flow intothe sheath-based filtering units. In some embodiments the fluid may bestreamed into the multiple filtering units simultaneously. In otherembodiments, the fluid may be streamed into the units sequentially (Step604). The fluid may be filtered in accordance with the methods describedabove and in any of FIGS. 3A and 4A (Step 606). The filtered fluid maybe removed from the units and directed into a sealed cover, optionallyfilling a cavity enclosed by the cover (Step 608). The filtered fluidmay be directed out of the sealed cover, and removed from themulti-sheath-based filter (Step 610).

Reference is now made to FIG. 6B which is a simplified flowchart of amethod for washing a multi-sheath-based filter, in accordance with anembodiment of the invention. In the method of FIG. 6B, a washing fluidis introduced at the top of a multi-sheath-based filter (Step 620). Thefluid may be directed into a sealed cover, optionally filling a cavityenclosed by the cover (Step 622). The fluid may flow into multiplefiltering units, corresponding any of units 100 and 200. In someembodiments the fluid may be streamed into the multiple filtering unitssimultaneously. In other embodiments, the fluid may be streamed into theunits sequentially (Step 624). The filtering may be washed in accordancewith the method described above and in any of FIGS. 3B and 4B (Step626). The washing fluid may be directed out the units into a sealedbody, optionally filling a cavity enclosed by the body (Step 628). Thewashing fluid may be directed out of the sealed body, and removed fromthe multi-sheath-based filter (Step 630).

To enhance the washing, a combination of water and air, or a combinationof a different liquid with air, may be used as the washing fluid. Theair may form bubbles in the water or the different fluid, and, thereby,the threads and their trapped impurities may be intermittently hit withwater and air, shocking them and assisting in releasing the impurities.Alternatively, only air may be used as the washing fluid, for at least acertain duration during the washing.

In this manner, a high overall thread-count is provided for enhancedfiltration. By dividing and separating the threads into multiple tubesindividually contained in multiple receptacles, a degree of separationis maintained between the threads, hindering thread entanglement.

In the description and claims of the application, each of the words“comprise” “include” and “have”, and forms thereof, are not necessarilylimited to members in a list with which the words may be associated. Inaddition, where there are inconsistencies between this application andany document incorporated by reference, it is hereby intended that thepresent application controls.

What is claimed is:
 1. A thread-based filter comprising: a tube having afirst end and a second end; a plate configured to provide one or morepassageways for fluid, wherein said plate is coupled to a rod; and athread-based filtration medium comprising multiple threads extendingbetween a first end of said medium and a second end of said medium,wherein: said medium is at least partially housed in said tube, thethreads of said medium are oriented lengthwise along the length of saidtube, with the first end of the medium oriented with the first end ofsaid tube, and the second end of said medium oriented with the secondend of said tube, the threads at the second end of said medium areattached to said plate, and the threads at the first end of said mediumare unattached and exposed, the rod is configured to provide astabilizing axis for lengthwise motion of said plate inside said tube;wherein the thread-based fluid filter is configured, in a filtrationmode, to: direct a fluid to flow lengthwise along the threads, from thefirst end of said medium to the second end of said medium, thereby: (a)pushing said plate and said medium towards the second end of said tube,(b) decreasing an inter-thread spacing of said medium at least in anarea adjacent the second end of said medium, and (c) trapping in thethreads impurities present in the fluid, thereby filtering the fluid,and remove the filtered fluid from the second end of said medium;wherein the thread-based fluid filter is configured, in a washing mode,to: introduce a washing fluid into the second end of said medium, directthe washing fluid to flow lengthwise along the threads from the secondend of said medium to the first end of said medium, thereby: (a) pushingsaid plate and said medium towards the first end of said tube, (b)increasing the inter-thread spacing of said medium at least in an areaadjacent the first end of said medium, by: (i) exposing, from the firstend of the tube, at least the area adjacent the first end of saidmedium, or (ii) exposing, from a narrow portion of said tube to a wideportion of said tube, at least the area adjacent the first end of themedium, and release the impurities trapped in the threads into thewashing fluid, thereby washing the medium, and remove the washing fluidand the released impurities from the first end of said tube.
 2. Thethread-based filter of claim 1, wherein said plate comprises aperipheral seal that prevents leakage between said tube and said plate.3. The thread-based filter of claim 1, wherein the washing fluid isintroduced in a continuous stream.
 4. The thread-based filter of claim1, wherein the washing fluid is introduced in pulses.
 5. Thethread-based filter of claim 1, wherein the washing fluid compriseswater.
 6. The thread-based filter of claim 1, wherein the washing fluidcomprises air.
 7. The thread-based filter of claim 1, wherein thewashing fluid comprises a combination of water and air, to form bubblesthat shock said medium and assist in the release of the impurities. 8.The thread-based filter of claim 1, wherein the lengthwise motion ofsaid plate inside the tube is solely by a pressure of the fluid to befiltered and the washing fluid.
 9. The thread-based filter of claim 1,wherein the multiple threads of said medium are each a monofilamentfiber.
 10. The thread-based filter of claim 9, wherein each of themonofilament fibers has a diameter of 200 to 250 micrometers.
 11. Thethread-based filter of claim 1, wherein the multiple threads of saidmedium are each a spun thread that is composed of multiple monofilamentfibers.
 12. The thread-based filter of claim 11, wherein each of themultiple monofilament fibers is made of polyester.
 13. The thread-basedfilter of claim 12, wherein each of the spun threads has a diameter of200 to 250 micrometers.